Signaling system



14 1927. June J. s. JAMMER SIGNALING SYSTEM qhv Il .w m m E.

TERE,

/m/en/or.' Jacob 5f Jammer 1,632,078 June 14 1927 J. s. JAMMER SIGNALING SYSTEM Filed June 2o, 1924 2 sheets-sheet 2 STATION W /m/enfor.' Jaca 5. Jammer Patented June 14, '81927.

JACOB S. JAMMER, OF NEW YORK,

Parrisia'r oFFicE.

N. Y., ASSIGNOR T WESTERN ELECTRIC COMPANY,

INCORPORATED, OF' NEW YORK, N. Y., A CORPORATION OF NEW YORK.

' SIGNALING SYSTEM.

Application nled .Tune 20,

This invention relates to signaling .systems and particularly to telephone signaling systems.

An object of the invention is to utilize voice currents for signaling purposes.

A related object of the invention 1s to simplif the operation and maintenance of a voice `operated signalin system.

Another object of the invention is to emlo ploy a single signaling circuit for a plurality of telephone lines.

In a specific embodiment of the invention, according to one feature, a current rectifier is bridged across the line at each terminal l5 station of a telephone system. When the operator at one station speaks, the voice currents incoming at the other station are rectiiied and caused to operate va relay to pass the signal to the receiving switchboard. When the operator at the receivlng end of the circuit inserts the plug in the answering jack the rectifier is removed from the line.

According to another, feature of the invention, a single signaling circuit is used for a plurality of telephone lines by providing means for automatically shifting the signaling circuit from a busy line to an idle line and for automatically shifting the signaling circuit back to the lirst line whensuch line again becomes idle.

The invention is applicable to both voice frequency and carrier current telephone systems, and, in fact, has wide application to various types of signaling systems where it is desired to utilize voice frequency currents for signaling purposes.

In the drawings, in which similar reference characters designate similar parts,

Fig. 1 is a diagrammatic view of a simplified form of voice frequency telephone system embodying the invention;

Fig. 2 is a diagrammatic view illustrating one terminal of a carrier current telephone system embodying the invention;

Fig. 3 is a diagrammatic view of one telniinal of a carrier telephone system including a plurality of trunk lines equipped with signaling circuits in accordance with the invention.

telephone system havin@ a station W and station E interconnected by a transmission line L. l

Since the system must be Worked in either 5 direction the apparatus at stations W and The system shown in Fig. 1 represents a 1924. serial no. 721,347.

E is similar. For the sake of clearness only the apparatus at station W will be described, the apparatus at station E being designated by simllar reference characters with .primes atlixed thereto.

In Fig. 1, a subscribers line (not shown) may terminate at a switchboard from which' a connection ma be extended to a cord'circuit A and a link circuit B in the usual manner. An operators telephone set 5 may 65 be connected to the cord circuit A by means of a listening key 6.

A sivnaling lamp 7 is controlled by a relay 8 1n the output of a rectifier 9 which may be of the three-element electron discharge type. The rectier 9 is coupled to the transmission line L by means of a transformer 10, and accordingly, incoming currents at station W passing into the rectifier 9 are rectified and caused to operate relay 76 8 to light lamp 7.

The link circuit B includes a plug 11 which when inserted in jack 12 establishes an operating circuit for a relay 13. The operation of relay 13 extinguishes lamp 7, 80 dlsconnects the line L from the input of rectifier `9, and connects line L to the operators cord circuit A, in a manner hereinafter to be described.

' Assuming that it is desired to transmit a 85 signal from station E to station W, the operator at station E inserts plug 11 into jack 12. This operates relay 13 over a circuit extending from ground, through plug 11', jack 12', winding of relay 13', battery 14', to 90 ground, relay 13 in operating attracting its armatures 15 and 16 to connect the jack 12 to the transmission line L. The operator then speaks on the circuit and the incoming currents at station W pass into rectifier 9 96 through the transformer 10. The rectified currents in the out ut of rectifier 9 operate relay 8 which esta lishes a circuit for the lamp 7 which may be traced from ground, through battery 17, lamp .7, armature and 10u contact of relay 8, armature 18 and lower contact of relay 13 to ground. The relay 8 is thereupon locked up over a circuit eX- tending from ground, through battery 19, winding of relay 8, armature and contact of relay 8, armature 18 and lower contact of relay l13 to ground.

Upon the illumination of lamp 7, the operator at station W inserts plug 11 into ]ack 12, thereby operating relay 13 over a circuit 110 "extending from-ground, through plug 11,

jack 12, winding of relay 13, battery 14 to ground. Relay 13, in operating, attracts its armatures 15, 16 and 18. The attraction of armature 18 opens the locking circuit of relay 8 and extinguishing lamp 7. The attraction of armatures and 16 disconnects line L from the input of rectifier 9 and connects'jack 12 to line L. By actuating listening key 6 the operator atstation W may converse with'the operator at station E, and may make connections with the appropriate subscribers telephone line in the usual manner.

The system described above is exceedingly simple and efficient in operation and has the advantage of simplified maintenance in that tuned relay circuits are entirely eliminated, thereby insuring the operation of the signaling relay 8 under varying transmissionV conditions.

In the system shown in Fig. 2 a single signaling circuit is employed common to a plurality of telephone lines. This feature of the invention is illustrated in connection with its application to a carrier current telehone system, but it will be obvious as the description proceeds that it is equally apf plicable to voice frequency telephone systems and to various other systems'differing widely from that illustrated.

Fig. 2 represents the west terminal station lV of a carrier telephone system connected to a multiplex line ML.V

The usual east terminal station, which is identical to terminal station W, is omitted for the sake of clearncss. A carrier telephone system of this general type, including both west and east terminal stations, as well as an intermediate repeater station, is illustrated diafrrammatically in Fig. 24 of an article entitled Carrier current telephony and telegraphy by Messrs. Colpitts and Blackwell, published in the Transactions of the American Institute of' Electrical Engineers, Vol. 40, 1921.

The terminal apparatus at sta-tion W comprises a plurality of transmitting channels TC TC2 and TC3 connected through a common transmittingr circuit TL to the main line ML, and a plurality of receiving channels RC RC2 and RC3 connected through a common receiving circuit RL to the main lille MIJ.

Carrier currents are utilized for transmission over the line ML and are grouped as to their frequencies, the higher frequencies, as a group, being utilized for transmission from west to east and the lower frequencies, as a group, being used for transmission from east to west.

Low frequency telephone lines L L2 and L are associated with channels TC,-RC,. TG2-RC2 and TCS-RC3, respectively, for simultaneous and independent communication over line ML with corresponding simi ilar lines at the distant station (not shown). The low frequency lines are provided with balancing artificial lines or networks N N., and N3, respective and with differential repeat-ing coils H H2 and H3, commonly known as hybrid coils, for enabling independent transmissionin the two directions between the lines and the high frequency terminal apparatus. v

Transmitting channel TC, includes a low ,pass filter. LPF a modulator M, and a band filter TBF,.v Similarly, transmitting channel TC2 includes a low pass filter LPF2, a modulator M2 and a band filter TBF2, while channel TC., includes low pass filter LPFa, modulator M3 and band filter TBF3.

Receiving channel RC, includes a low pass filter L,PF a demodulator D, and. a band,

filter RBF,. Similarly, channel 4RCz includes a low pass filter L,PF, a demodulator D., and band filter RBFZ, while channel RC, includes low pass filter L,PF3, demodulator D, and band filter RBF3.

The various filters employed throughout the system may be designed in accordance with the principles set forth in the U. S. patent to Campbell, No. 1,227,113, issued hlay 22, 1917.

The modulators associated with the various transmitting channels throughout the system may be of any well known type, such as that disclosed in the U. S. patent to Van der Bijl, No. 1,350,752, issued August 24, 1920. The various demodulators may be of th'cwell known vacuum tube detector ty e lshown in Fig. 42 ofthe Colpitts and Black'- well article, supra.

The carrier system outlined above is of the type in which the carrier current is transmitted continuously, as distinguished from the type in which the carrier is snppressed from transmission. A system of this general character is described in connection with Fig. 42 of the Colpitts and Blackwell article, supra.

In this system, carrier currents of the frequency assigned to channel TC, are supplied from a source O, to the modulator M, wherein'they are modulated by voice frequency currents from the lowfrequency line L,. Carrier sources C, and 0 are similarly associated with modulators M2 and M3, respectively.

The various low pass filters associated with the terminal transmitting and receiving channels arix designed to transmit with substantially negligible attenuation all curlrents within the voice frequency ran-ge and to suppress from transmission currents of all frequencies lying outside such range.

The various band filters associated with the terminal transmitting and receiving channels are so designedfhat they will transmit bands of frequencies including the carrier assigned to the respective channels vas well as o ne of the side bands, either the upper or lower as desired, and will suppress from transmission frequencies lying outside such bands. L

Voice frequency currents originating, for instance, in the low frequency line L' pass through Athe associated hybrid coil H, through low pass filter LPF, into modulator1 M,. There is likewise fed into the modulator the carrier current from the oscillator O, as described above. Of the components of modulation appearing in the output circuit of the modulator M, the transmitting band filter TBF, suppresses all except one side band, for example the upper side band, and the carrier, which it transmits or passes into the common transmitting circuit TL. The currents thus transmitted from channel TC, and the other transmitting' channels then pass through transformer T to the multiplex line ML. The incoming currents at the distant station (not shown) are picked up by the receiving band filter inthe appropriate channel, are demodulated, andl are passed on to the associated low frequency apparatus in the usual manner.

The system of Fig. 2 is so arranged that a single rectifier circuit and voice operated relay is utilized to operate lamps or other signaling devices for a plurality of telephone lines. This is accomplished by providing means for automatically shifting the signal controlling mechanisms from a busy to an idle line, and for automatically shifting the signal controlling mechanisms back to the first line when such line again becomes idle.

It will be understood that the operators telephone set 5 and switching mechanisms associated with the low frequency telephone line L, are similar to the operators set and switching mechanismshown in Fig. 1, and

that similar apparatus is also associated with low frequency lines L2 and L3 but are omitted from the the drawings for the sake of clearness.

When the operator at the distant station plugs in and talks over the transmitting channel which cooperates with receiving channel RC, at station W, the currents received at station W, consisting of one side band accompanied by its carrier, are selectively passed through the receiving band filter RBF, and are then amplified and demodulated in the demodulator 1),. The voice frequency currents appearing in the output circuit of the deinodulator D, are selected from the other components of demodulation by the low pass filter L,Pl-`, from which point in the circuit they pass through the low frequency hybrid -coil H, to the voice frequency line L,.

The incoming voice current-s on line L, pass through armatures 22 and 23 and their associated upper contacts of relay 13, armatures and ,contacts 25 and 26 of relay 27, transformer 10 to the input of rectifier 9.

The rectified currents in the output of'rectier 9 operate relay 8 thus completing an energizingc'lcuit for relay 28 which may be traced from ground,'through armature and contact of relay 8, conductor 30, winding of relay. 28, battery 29, to ground. Relay 28 in operating lights lamv 7 over a circuit extending from groun through battery 17, lamp 7, armature and contact ofrelay 28,

lower contact and armature 24 of relay 13 tol ground. Relay 28 is thereupon locked up over a circuit extendingfrom ground,

through battery 29, winding, armature and contact of relay 28, armature 24 and lower contact of relay 13, to ground. Although relaysl 228 and 328 are likewise operated, the lamps 207 and 307 are not lighted due to the fact that their energizing circuits are open at the upper contact associated with armature 24 of relay 13 and the energizing circuit of lamp 307 is also'open at the upper contact associated with armature 224 of relay 213. i

When the operator inserts plug 11 into jack 12, relay 13 is operated over a circuit extending from ground, through plug 11, jack 12, winding of relay 13, battery 14, t0 ground. Relay 13in attracting its armatures 22 and 23 disconnects the line L, from the input of rectifier 9 andconnects the jack 12 tothe lineL,. Relay 13 in operating also attracts its armature 21 thereby removing a shortcircuit across transmitting channel TC, andv enabling the operator to talk through the hybrid coil H, into channel TC,. Relay 13 in operating also moves its armature 24 from its ylowerl to its upper contact-` thereby opening the locking circuit of relay 28 and extinguishing lamp 7.

An operatinor circuit for relay 27 is likewise established by the insertion of plug 11 into jack 12, this circuit extending from ground, through plug 11, jack 12. winding of relay 27, battery 31 to ground. Relay 27in operating attracts its armatures, opening contacts 25 and 26 and closing contacts 32 and 33, thus shifting the rectifier 9 and associated signal controlling mechanisms from line L, to line L2.

Vhen the conversation is completed on line L, and plug 1l is removed from jack 12, relays 13 and 27 are deencrgized and, accordingly, the circuit is restored to the original normal condition shown in the drawing. If, however, the operator at the distant statlon wishes to send through another call to station We while the line L, is busy', the operator at the distant station will take up the circuit associated with line L, and speak. Theincoming currents at appear in the low frequency line L 2 in the manner described above. These volce currents pass through armatures 222, 223 and their associated upper contacts of relay 213, contacts 225 and 226 and armatures of relay 227, contacts 32, 33 and armatures of relay 27, transformer 10 to the input of rectifier 9. The output currents of rectifier 9 operate relay 8, thereby establishing an operating circuit for relay 228 which extends from ground, through armatureand contact of relay 8, conductor 30, windlng of relay 228, battery 229 to ground. Relay 228 in attracting its armature lights lamp 207 over a circuit extending from ground, through battery 217, lamp 207, armature and contact of relay 228, armature 224 and lower Contact of relay 213, conductor 35, armature 24 and upper contact associated therewith of relay 13 to ground. Relay 228 is thereupon locked up over a circuit extending from ground, through battery 229, Winding, armature and contact of relay 228, armature 224 and lower contact of relay 213, conductor 35, armature 24 and upper contact associated therewith of relay 13 to ground. Although relays 28 and 328 are also operated over circuits similar to the energizing circuit of relay 228, lamps 7 and 307 are not lighted due to the fact that the circuit of lamp 7.1s open at the lower contact associated )vith armature 21 of relay 13, and the circuit of lamp 307 is open at the upper cont-act associated with armature 224 or relay 213.

The'operator at the station W. noting that lamp 207 is illuminated, inserts a plug similar to plug 11 into answering jack 212, thus operating relays 213 and 227 over circuits similar to those described above in connection with relays 13 and 27. Relay 213 in attracting its armatures 222 and 223 disconnects line L, from the input of rectifier 9 and connects jack 212 to the line L2- Armature 221 is also attracted to remove the short circuit across transmitting channel TC2 thereby enabling the operator to talk over the circuit. Armature 224 is also` moved from its lower to its upper contact, thereby opening` the locking circuit of relay 228 and extinguishing lamp 207. Relay 227 in operating attracts its armatures, opening contacts 225 and 226 and closing contacts 232 and 233, thus shifting the rectifier 9 and associated signal controlling mechanisms from line L2 to line L3.

If the conversation on line L, is completed and plug 11 is removed from jack 12 while line L, is still busy, relays 13 and 27 will he restored to the normal condition shown in the drawing and rectifier 9 and the associated signaling mechanisms will be. restored to line L,.- thereby enablingr a signal to be transmitted over this line while line L2 is still busy. Likewise, when the conversation is completed ou line Lz and the plug is re moved from jack 212 the circuits associated with line L2 are restored to'normal, thus en abling another signal to be transmitted over this line if line Ll is still busy, or if line L, has again become bu in the meantime. If, however, lines Ll an L2 are both busy, sigp, nals may then be transmitted over line L,.

In the latter case, the incoming voice currents on line L3 pass through armatures 322 and of relay 313, contacts 232 and 233 and armatures of relay 227 (since relay 227 is energized), contacts 32 and 33 and armatures of relav 27 (since relay 27 is energized), transformer 10, to the input of rectilier 9, thus operating relay 8. Relay 8 in operating establishes an energizing circuit for relay 328 over an obvious circuit, and relay 328, in operating lights lamp 307 over a cir cuit extending from ground, through battery 317, lamp 307, armature and contact of relay 328, armature 324 and lower contact of relay 313, armature 221 and upper contact associated therewith of relay 213, conductor 35, armature 24 and upper contact associated therewith of relay 13 to ground. A locking circuit is likewise established for relay 328, thus maintaining lamp 307 illuminated until the operator inserts a plug similar to the plug 11 into jack 312 at which time the relay 313 is operated in the manner described in connection with relays 13 and 213. Relay 313 in attracting its armatures 322 and 323 disconnects line L3 from the input of rectiiier 9 and connects jack 312 to line L3. The operation of armature 324 opens the lock- 10 ing circuit of relay 328 and extinguishes lamp 307. The operation of armature 321 removes the short circuit across transmitting channel TCI, and enables voice currents orig inating in line L3 to pass into transmitting 105 channel TCW If desired, relays 13, 27, 213, 227 and 313 may be of the slow-releasing type so that when the circuit of rectifier 9 has been trans` ferred from one line to another, say from 110 line L1 to line L2 the rectifier 9 will remain associated with line L2 long enough to illuniinate. lain'p 207 if a signal has been sent through on line L2 at the very instant that convelsation on line Ll is completed and 115 plug 11 is removed from jack 12.

Fig. 3 shows a carrier current telephone system including a plurality oftrunk lines equipped with signaling s vstems of the type shown in Fig. 2. Trunk lines 1 to 4, inclu- 20 sive. are connected through a comon transmitting circuit TLl and a common receiving circuitbRL1 to the multiplex line MLl. Similarly, trunk lines 5, 6, 7, etc. are connected through a common transmitting circuit TL.l 125 and a common receiving circuit RL2 to the multiplex line ML2. Additional trunk lines may also be provided and may be associated with either of the lines ML, or ML. or may be associated with still another multiplex` l `ncaaova line', not shown. Band filters BF1, ,'BFZ, BFS, etc., are associated withtrunk lines 1, 2, 3, etc. and serve to separate the groups of carrier Waves to the respective trunk circuits. These filters may be of the band filter type disclosed in the Campbell patent, supra..

A rectifier circuit R, is' associated with trunk lines 1, 4 and 7 in a manner' identicai to that in which rectifier 9 and associated switching mechanisms of Fig; 2'is associated with line-L L2 and L3 of Fig. 2. Switching circuits Sw S4 and S7 similar to the switching circuits associated with lines L L2 and Ln of Fig. 2 are provided for shifting the rectifier circuit R, from one trunk line to' the other. Similarly, a rectifier circuit R2 and switching circuits S2 and S5 are associated with trunk lines 2 and 5, while rectifier. circuit R3 and switching circuits S3 and Sa are associated with trunk lines 3 and 6.

In operating the system of Fig. 3, the-operators will be instructedY to use the circuits in sequence. When a signal has been passed over trunk l and answered, rectifier circuit R1 will be automatically shifted to trunk 4. Likewise, when the signal has been passed over trunk 2 the rectifier circuit R2 will be shifted to trunk 5, and when a signal has been passed over trunk 3 the rectifier circuit R3 will be shifted to trunk 6,*etc. When trunk 1 becomes idle, rectifier circuit R, which has been shifted to trunk 4 is automatically restored to trunk 1, etc.

Since many changes may be madein the system herein shown' and described without departing from the spirit of the invention, it is to be understood that the invention is not to be limited in any way by the disclosure, except as defined by the scope of the appended claims.

What is claimed is:

1. In a signaling system, a transmission line, a rectifier connected to said line, a relay in the out ut of said rectifier, a signal controlled by said relay, a telephone set, and

switching means for disconnecting said rectifier from said line and for simultaneously connect-ing said telephone set to said line.

2. In a signaling system, a transmission line, a rectifier connected to said line, a relayl in the output of said rectifier, a siena-ling circuit controlled by said relay, a telephone set, and switching means for disconnecting said rectifier from said line and connecting said telephone set to said line, and for simultaneously opening said signaling circuit.

3. In a signaling system, a telephone line, a terminal station associated with said line, a cord circuit at said terminal station, a

rectifier circuit bridged across said line at.

said terminal station to rectify incoming voice currents, a relay in the outputof said rectifier circuit, a signal controlled by said relay, and switching means to disconnect said line from said rectifiercircuit and to connect said line -to said cord c1rcu1t. 4. In a signaling system, a telephone llne,

a terlninal station asso iated withsaid line a cord vcircuit at said terminal station, a rectifier circuit bridged across said line to rectify incomingvo1ce'currents,'a relay in the output of said rectifier circuit, .a signal controlledby said relay', a relay adapted to disconnect said line from said 'rectifier circuit and to connect said line to'said cord circuit, and switching means associated with tion, and switching means for disconnecting' said rectifier from said line and for simultaneously connecting said telephone set to said line. v l

6. In a signaling system, a plurality of transmission lines, a voice operated signal associated with each of said lines and controlled by current received over the respective line, a signal controlling circuitassocia'ted with one of said lines for controlling .the actuation of the respective si nal, and means for disconnecting said signa controlling circuit from said last mentioned line and for connecting it to another-of said lines.

7. In a signaling system, a plurality of transmission lines, a signal associated with each of said lines, a voice operated signal controlling circuit associated with one of said lines, and means for disconnecting said signal controlling circuit from one of said lines and for connecting it to another of said lines.

8. In a signaling system, a plurality of transmission lines, a signal associated withv each of said lines, a voice operated signal controlling circuit associated with one of said lines, and automatic .means operative under predetermined conditions to disconnect said signal controlling circuit from one of said'lines and to connect it to another of said lines. a

9.'In a signaling system, a plurality of transmission lines, a signaling 'device associated with each of said lines, a rectifier circuit normally connected to one of said lines to rectify voice currents transmitted thereover, means controlled by the currentin the output of said rectifier circuit for energlzmg the associated signaling device, and means for disconnecting said rectifier circuit from one of said lines and connecting it to another of said lines.

y10. In a signaling system, -a plurality of transmission lines, a signaling device associated with each of said lines, a rectifier connected to one of said lines, means controlled by the current in the output of said rectifier for energizing the associated signaling device, a telephone set, switching means for disconnecting said rectifier from the line to which it is connected andconnecting saidtelephone set to said line, and means controlled by said switching means to connect said rectifier to another of said lines.

1l. In a signaling system, a plurality 0f transmission lines, a signaling circuit associated with each of said lines, a rectifier connected to one of said lines, means controlled by the current in the output-of said rectifier for energizing the associated signaling circuit, a telephone set, switching means for disconnecting said rectifier from the line to which it is connected and connecting said telephone set to said line, means controlled by said switching means for opening the signaling circuit of said first line, and means also controlled by said switching means to connect said rectifier to another of said lines.

l2. In a carrier wave signaling system, a multiplex carrier line employing carrier Waves of different frequencies, a plurality of low frequency lines associated with said multiplex line, a signaling device associated with each of said 10W frequency lines and controlled by current received over the respective line, a signal controlling circuit, and

means for associating said circuit with any of said low frequency lines under predetermined conditions.

13. In a ,carrier wave signaling system, a

multiplex carrier line employing carrier waves of different frequencies, a plurality of incoming channels associated with said multiplex line,a signaling device associated with each ofsaid channels and controlled by current received over the respective `channel, a signal receiving circuit connected t0 one of'said channels to control the associated signaling device, and means for disconnecting said signal controlling circuit from said last mentioned channel and for connecting it to another of said channels. y

14. In a carrier Wave signaling system, a multiplex carrier line employing carrier Waves of different frequencies, a low'frcquency line associated with said multiplex line, a rectifier circuit bridged across said low frequency line to rectify incoming voice currents, a relay in the output of said rectifier circuit, a signaling device energized by said relay, a cord circuit, and switching means to disconnect said low frequency line from said rectifier circuit and to connect it to said cord circuit, and means also controlled by said switching means to deenergize said signaling device.

In witness whereof, I hereunto subscribe my name this 14th day of June A. D., 1924.

JACOB S. J AMMER. 

